Tomato growers in Florida and other states accuse Mexican farmers of illegal dumping. The Commerce Department may side with them, though some U.S. groups disagree.

Siding with him were numerous U.S. agricultural and retail organizations including the National Restaurant Assn. and Wal-Mart.

"A potential trade disruption with Mexico could have a devastating impact on U.S. farmers, manufacturers, and service providers and their employees who collectively export hundreds of billions of dollars in goods and services annually to Mexico," the U.S. Chamber of Commerce wrote in a letter last month to acting Commerce Secretary Rebecca Blank.

The Florida growers, meanwhile, had their own booster club, including a bipartisan group of Florida legislators, who said in letters to Blank that the "predatory actions" of Mexican tomato growers were hurting domestic production. A similarly bipartisan group of Arizonans, led by Republican Sen. John McCain, backed the Mexican tomato.

The Floridians welcomed the Commerce move.

The "preliminary decision is welcome news to domestic growers and the workers who have suffered under an outdated and failed agreement governing trade in fresh tomatoes with Mexico," Reggie Brown, executive director of the Florida Tomato Exchange, said in a statement.

Some California growers also lauded the move.

Donna Vaughan, a stakeholder in Live Oak Farms, a tomato grower in Merced County, said her firm had found itself competing against Mexican growers in recent years and that it was losing. Mexican growers have ramped up production in summer months, cutting into California's tomato growing season.

"It's been difficult to compete," she said. "If the playing field was fair, I'd have no issues. But the playing field doesn't seem to be fair."

The 1996 agreement that the Commerce decision would scrap grew out of the 1994 North American Free Trade Agreement, which opened the door to more abundant tomato exports to the U.S. from Mexico by eliminating tariffs. NAFTA also set up mechanisms for settling the many trade disputes that followed, and this latest spat over the tomato may yet end up being resolved that way.